Draft-controlling apparatus for steam-boilers.



W. E. SNOW. DRAFT OONTROLLING APPARATUS FOR STEAM BOILFRS. APPLICATION FILED JAN.10,1906.

1,034,039. I I PatentedJuly30,1912.

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W. E. SNOW. DRAFT CONTROLLING APPARATUS FOR STEAM BOILERS.

APPLIGATION FILED JAN.10, 1906.

1,034,039. Patented July 30,1912.

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DRAFT CONTROLLING APPARATUS FOR STEAM BOILERS.

APPLICATION FILED JAN. 10, 1906.

1,034,039, Patented July 30, 1912.

4 SHEBTSrSHEETS jrpventar:

W. E. SNOW.

DRAFT CONTROLLING APPARATUS FOR STEAM BOILERS.

APPLICATION FILED JAN.10,1906.

Tm34 089. Patented July 30, 1912.

4 SHBETS-SHEET 4.

UNITED STATES PATENT OFFICE.

WILLIAM E. SNOW, OF HYDE PARK, MASSACHUSETTS, ASSIGNOR TO B. F. STURTE- VANT COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHU- SETTS.

DRAFT-CONTROLLING APPARATUS FOR STEAM-BOILERS.

Specification of Letters Patent.

Patented July 30, 1912.

Application filed January 10, 1906. Serial No. 295,350.

To all whom it may concern:

Be it known that I, WILLIAM E. SNOW, a citizen of the United States, residing at Hyde Park, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Draft- Controlling Apparatus for Steam-Boilers; and I do hereby declare the following to be a. full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to an improvement in draft controlling apparatus for steam boilers.

In stationary boiler plants it is now the common practice to provide a blower or exhauster operated by a steam engine for creating a forced or induced draft for the furnace. These engines have not commonly been provided with speed governors, but are usually regulated solely by a hand-regulated throttle valve. Draft engines unprovided with a governor are open to the objection due to the liability of the engine to run away or race in case the damper be closed, because of the taking of the load olf the engine. This fact has led to the demand that such engines be provided with governors. Now it is desirable to provide automatic means controlled by the steam pressure in the boiler for adjusting the valve gear of the blower or exhauster driving engine to vary the speed of the engine inversely with the variations of the boiler pressure so as to increase the draft when the pressure falls and decrease the draft when the pressure rises, whereby a very constant steam pressure may be maintained.

The applicant has produced an improved draft-controlling apparatus for steam boilers in which the blower or exhauster is driven by a governed steam engine, and in which means are provided for varying the normal speed of the engine inversely with the fluctuations of the boiler pressure; that is to say, if the engine is set to run at a certain number of revolutions for a certain boiler pressure, which number of revolu tions may be called the critical speed of the engine, with an increase in the boiler pressure, the critical speed of the engine will be reduced and the engine will govern itself to the new critical speed.

To the above end the present invention consists in the device and combinations of devices described and particularly defined in the claims.

In the accompanying drawings illustrat ing the preferred form of the invention, Figure 1 is a diagrammatic elevation of a boiler, exhauster and engine for driving the exhauster; Fig. 2 is a side elevation of a portion of the fly-wheel of the engine with the governor thereon; Fig. 3 is a sectional elevation taken on the irregular line 33 Fig. 2; and Fig. 4 is a section on the line 4-4 Fig. 3.

The boiler 1 discharges its steam through the steam main 2 and the gases of combustion from the boiler furnace are discharged throughthe trunk 3 to the exhaust fan 4 driven by the steam engine 5, which gases are discharged up the stack 6. The engine is supplied wit-h steam by the pipe 7 leading from the steam main to the steam chest of the engine 5. The operation of the governor is affected by a cont-rivance attached to it for varying the critical speed of the governor, which is operated by the boiler pressure conveyed thereto through the pipe 8.

The specific embodiment of the contrivance for varying the critical speed of the governor will be described in connection with the construction and operation of the governor, which, in and of Itself, forms no part of the invention, being merely illustrated and described herein for the purpose of giving a complete description of the construction in which the invention is preferably embodied, it being understood, however, that it is within thepurview of the in-- vention to employ other and different forms of governor, and to control the critical speed thereof by other and diiferent means from those illustrated in the drawings and particularly herein described.

The governor, (see Fig. 2) is of the variablethrow type. The governor lever 9 is pivoted upon a pin 10 secured in the flywheel 11. The governor lever is provided with weights 12 and 13 at its opposite ends, and a spring 14 adjustably secured to the governor lever at 15 and to one end of a lever 16 pivoted at 17 to one of the arms of the fly-wheel, normally tends to rotate the governor lever 9 on its pivot 0 in the direction to move the eccentric pin hereinafter referred to, which actuates the alve, to its position of greatest throw.

The governor as thus far described, excluding the method of attachment of the end of the spring to the fly-wheel, is the wellknown Rites governor. This governor is adjusted by increasing or decreasing the tension of the spring 14 or by increasing or decreasing the weights 12 and 13. With given weights 12 and 13 the critical speed of the engine may be increased by increasing the. tension on the spring 14. This is permanently accomplished by means of the usual adjusting screw for adjusting the point of attachment 15 of the spring to the governor lever 9. For the purpose of vary ing the critical speed of the engine during its operation means have been provided for increasing and decreasing the tension on this spring through suitable connections operated by the boiler pressure. These means are described as follows :The lever 16 to one end of which the spring 14: is connected is pivoted at 17 to one of the arms of the fiy-wheel 11, and its opposite end is connected by means of a link 18 with a bell crank lever 19 pivoted at 20 to the hub of the fly-wheel 11. The bell crank lever 19 is articulated with a plunger 21 mounted in a bearing projecting from the hub of the fly-wheel, the head 22 of which is adapted to bear upon a regulating plate 23, which is supported in suitable housings projecting from the frame of the engine. This regulating plate is adapted to be moved in and out either automatically or by hand. The hand-operated means for moving the regulating plate comprise a fork 21- having its two arms extended down upon opposite sides of the plate 23, to which they are pivotally attached. The stem 25 of the fork 24 is received in a bearing in the housing or frame of the engine and provided with a rack engaged by a pinion 26 secured. to the end of a shaft 27 mounted in a bearing 23 in the housing, and carries upon its outer end a hand wheel 29. A clamp 30 is provided to hold the hand wheel stationary in any adjusted position as desired. The above-described arrangement is such that by turning the hand wheel 29 to the right the regulating plate 23 is moved to the left,

' and as a consequence the bell crank lever 19 is turned so as to pull on the link 18 and thereby exert an increased tension upon the spring 14, which operates to increase the critical-speed of the engine. Conversely, turning the hand wheel 29 to the left operates to decrease the critical speed of the engine.

' The automatic means for varying the criti cal speed of the engine comprise a bell crank lever 31 pivoted to the housing and connected, at its upper end, to the plate 23,

and at its other end, by means of a link 32, with a lever 33 actuated by a diaphragm apparatus 34 connected by the pipe 8 with the boiler 1. The clamp 30 being released, the apparatus will regulate itself in accordance with variations of the boiler pressure. Thus, forexample, when the boiler pressure increases, the diaphragm apparatus 34 will permit the outer end of the lever 33 to risett-hereby permitting the plate 23, through its connections with the level 33, to move to the right as viewed in Fig 3, whereby the speed of the engine is reduced by relaxation of the tension of the spring 14-.

From the foregoing description of the construction of the governor and the contrivance connected therewith for varying the tension of the governor spring, it will be seen that the engine is provided with two independently controlled means for varying the valve motion; first, the governor, which by its movements will move the eccentric pin 35 to increase or decrease its throw, whereby the speed of the engine is maintained constant, irrespective of variation in the load or steam pressure, and the lever contrivance, by which the tension of the governor spring may be varied without movement of the governor lever. The lever contrivance, it will be observed, operates to decrease the tension on the governor spring upon the increase of steam pressure in the boiler. This varies the critical speed of the engine, that is, its governed speed, and causes the engine to slow down when the boiler pressure rises abovethe proper pressure, and conversely upon a fall of the pressure in the boiler, the governor spring is increased and thereby the speed of the engine is increased. From the foregoing description it will also be seen that the engine is provided with means for varying the speed of the engine inversely to the boiler pressure, which operate to maintain the proper speed irrespective of variations in the load on the engine.

In the illustrated embodiment of the invention the speed of the. engine is varied by varying the pointof cutoff, whereby the economical advantages incident to this method of the use of steam are secured and while it is considered that the embodiments of the invention'are to be preferred which secure these advantages, still, it is to be understood that the invention is not necessarily limited thereto, as it may be embodied in constructions comprising a. throttle governor such, for example, as the governor of the Waters type.

Having thus described the invention, what is claimed is 1. Draft controlling apparatus tor steam boilers, having, in combination, a boiler, a furnace, a blower to create a forced draft for the furnace, a steam engine for driving the blower, a steam valve to regulate the admission of steam to said engine, a centrifugal governor actuated by the speed of the blower and connected directly to the steam valve to automatically maintain the blower at a predetermined speed irrespective of the load on the blower, said centrifugal governor comprising a spring whose tension determines the speed at which the governor maintains the blower, and means con trolled by the pressure of the steam in the boiler to vary the tension of said spring to cause the centrifugal governor to vary the speed at which it maintains the blower inversely with the boiler pressure.

2. Draft controlling apparatus for steam boilers, having, in combination, a boiler, a furnace, a blower to create a forced draft for the furnace, a steam engine for driving the blower, a steam valve to regulate the admission of steam to said blower engine, a governor actuated by the speed of the blower and connected directly to the steam valve to automatically maintain the blower at a constant speed irrespective of the load on the blower, and means connected to said governor and controlled by the pressure of the steam in the boiler to act as a secondary regulation of said governor to'cause said governor to decrease the speed at which it maintains the blower as the boiler pressure increases.

In testimony whereof I aflix my signature, in presence of two witnesses.

WILLIAM E. SNOW.

. Witnesses:

FARNUM F. DORSEY,

ANNE G. HOLT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

